The major aim of this proposal is to identify the neuroendocrine mechanisms responsible for the initiation and maintenance of the extra-gonadal suppression of the gonadotropin secretion during prepubertal development in the rhesus monkey. This inhibitory control system appears to interrupt or restrain the hypothalamic mechanism responsible for the intermittent secretion of GnRH and thereby results in the protracted delay in the onset of puberty. In this regard, the role of the pineal gland and other extra-hypothalamic areas of the brain will be investigated using microneurosurgical, stereotaxic and roentgenographic techniques. The effect of adrenalectomy on the neonatal developmental pattern of gonadotropin secretion will also be studied. Since the neuroendocrine mechanisms underlying the onset of puberty in the rhesus monkey and in man appear similar, the proposed studies may have direct relevance to the human situation.